Cans and method for canning



Oct. 25, 1966 A, R. DANDREA cANs AND METHOD Fon CANNING Filed April 20, 1964 INVENTOR ggg" Anm-:Lo RnLPH D'ANnRE/a B-ALA/M m ATTORNEY5 United States Patent O 3,281,008 CANS AND METHOD FOR CANNING Angelo Ralph DAndrea, 6357 Greene St., Philadelphia, Pa. Filed Apr. 20, 1964, Ser. No. 361,007 2 Claims. (Cl. 220-63) This invention relates to a new metal container, and a new method :of preserving foods or beverages, particularly acid containing foods or beverages, such as carbonated commodities, e.g. beer, soda water, soft drinks and fruit juices, fruits and vegetables.

Metal containers of this type usually consist of a cylindrical side wall and two end walls consisting of the same metal, generally tin plate, i.e. an iron plate coated with tin. In later days also aluminum cans have come into use.

In order to prevent attack of the preserved materials, the inner Walls of the container `are coated with a lacquer c-oating, artificial resin or plastic, e.g. vinyl acetate resins. During the manufacturing of the containers, this coating of lacquer or plastic may be and usually is damaged, so that the underlying metal is exposed to the contents of the preserved foods or beverages.l This damaging is due to the seaming 1operation or to the filling and closing operation or to a blow of some kind to the walls of the container.

When the Lacquer or plastic coating is locally damaged, the underlying metal, e.g. the tin plate, or aluminum, or other metal or alloy is exposed to the food or beverages. In some cases even the tin plate, coating the steel base, is ruptured or abraded and then the steel base is exposed to food or beverage and these damages result into a shortened shelf life and lruining of the preserved product. Salts may be produced, which impart an bjectionable taste to the preserved product.

This invention eliminates the above-mentioned drawbacks.

The metal new container or can -for preserving foods or beverages according to the present invention hasa wall or part of a wall of the container of a metal of higher electromotive anodic potential than the rest of the metal -of the container. In the galvanic series, the most suitable metals, listed in order of decreasing anodic potential are magnesium, aluminum, manganese, zinc, chromium, ir-on, nickel, tin, lead, and copper. However, other metals, such as stainless steel, for example, may be used and particularly by the use of alloys suitable combinations of metals and/or alloys may be easily applied by the expert.

The walls of the container or can of the present invention are covered with a coating, e.g. a permeable lacquer, artificial resin or plastic. One or more of the walls of the container, e.g. the end wall, may be of aluminum and the other walls, e.g. the side Wall and the other end wall, may be of tin plate, i.e. iron plate coated with tin, or vice versa. Moreover, all of the interior walls of the container may be coated by a layer of lacquer or plastic, preferably permeable for metal ions, such as a polyvinyl coating.

The use lof a suitable permeable lacquer, such as vinyl lacquer, will diminish the electrochemical conductivity produ-ced 'by a cu-rrent flowing in the proper direction so as to provide cathodic protection to the tin plate or the steel or other suitable metal =or .alloy of the can.

In the present invention, because of the permeability of the synthetic resin coatings, there is contact of the electrolyte; namely, the beer, carbonated beverage or other contents, such as foods, etc. of the can with b-oth the aluminum or other suitable metal surfaces [and the steel or tin or other suitable different metallic surfaces ICC of the body of the can. As an example, since aluminum is negative to iron and tin, it acts as an anode, and by going into s-olution, it provides cathodic protection to the tin and iron on the interior of the can body. If the aluminum surfaces were lacquered with 1a completely protective coating (that is a coating which had no permeability whatsoever), there would be no action because it would be completely isolated from this action. Other metals, of course, mentioned herein provide the cathodic protection to the can.

In the present invention, the partially permeable synthetic resin lacquer will permit the electrolyte topenetrate and come in Vcontact with the basic metal. However,

. the amount of acidic electrolyte which enters by permeating the lacquer forms an aluminum salt which, in the presence of la large amount of excess metal, becomes a basic salt with relatively poor permeability characteristics. Hence, the formation of this basic salt, which might be referred to as a mixture of aluminum hydrate and an aluminum salt, impedes the continuing action and slows down the electrolytic conduction through the ilm of the ions which are necessary to carry the current. There is, however, a small amount of actual conduction by these ions penetrating the partially permeable coating of the lacquer and this maintains the protective electrical potential which suppresses the solution of the undesirable ions such as iron and tin. It is well known in the art that very small traces, in the neighborhood of two to three parts per million of iron, is damaging to the avor and clarity of the beer and other beverages. These small traces also affect the color and flavor of most carbonated beverages. On the other hand, aluminum is a relatively inocuous ion, as indicated by the tfact that that aluminum is used widely in the food packaging industry for cooking utensils. i

Cans of the present invention which were packed in accordance with the practice of this invention, were found to be in excellent shape at the end of the two year period.

In case of damage of the permeable lacquer or plastic coating and even of the tin coating, the metal exposed will attack the contents of the container due to which metal salts may be dissolved into the food or beverage. Due to the presence of the different metal, having a higher anodic potential, these metal ions will be taken up by the other metal due to the permeable coating thereon, so that the taste of the preserved product is not objectionably altered. Consequently, the shelf life or the keeping qualities of the Icontainer contents is considerably much longer than known cans. The shelf life of canned beer and carbonated beverages which is normally approximately six months is increased to several years. Canned frozen orange concentrate which can normally be canned, at most eighteen months, appears to be still perfect in taste after iive years, when canned in .a can according to the present invention.

One effect of the invention is obtained when the frangible sheet consists of aluminum foil or steel foil and the rest of the container of tin plate or aluminum. The aluminum sheet or Steel sheet, as Well -as the tin plate or .aluminum walls are coated With a permeable lacquer or fVinyl permeable plastic.

In case of carbonated beverages such as beer, soda Water or soft drinks, the carbonic acid may collect over the liquid and there will be a head space of approximately 1.5 mm. between the liquid and the top of the container. In that event, lanother part of the well, e.g. the bottom end of the container, may, if used, be wholly or par tially of the metal having a different negative rating than the top or upper end of the can.

Merely for illustrative purposes, several forms of the present invention are depicted in the attached drawing wherein:

FIG. 1 is a vertical cross-sectional view of the container or can of the present invention;

FIG. 2 is .an enlarged vertical fragmentary section on the lines 2--2 of FIG. 1 looking in the direction of the arrows;

FIG. 3 is an enlarged vertical fragmentary section of the upper portion of a modified can or container; and

FIG. 4 is an enlarged vertical fragmentary section of the upper portion of a further embodiment of the can or container of the present invention.

Specifically, in the drawings, FIGS. 1 and 2, there is disclosed an yaluminum container A which preferably has an integral rbottom 1 and a lid or closure generally renoted C, of tin plate. The inner Iwalls of the container have -applied thereto a permeable lacquer L, such as a vinyl lacquer. Also, the inner surface of the lid C is likewise c-oated with preferably the same permeable vinyl lacquer L. 'This lid or closure C is hermetically sealed yat the upper end of the can body A in the usual manner, such `as by double seaming and by conventional dei vices and machinery.

It will be noted from FIG. 2 that the permeable lacquer extends into the double seam S. Also, in FIGS. 1 and 2, it will be noted that there is a head space H, the size of which has been exaggerated in these Views as well as having been done likewise in FIGS. 3 and 4.

As regards the modification of the invention in FIG. 3, the can or container A is the same as that defined with regard to FIGS. 1 and 2 and, also, the closure or lid C is the same as that defined in FIGS. l and 2 as well as the seam S and the lacquer coatings L and L. However, in FIG. 3 where the body of the can or container A is of aluminum, the closure C of aluminum has lapplied in any suitable manner to its inner surface, a lining of steel foil F. This steel foil F is of a. thickness substantially that of aluminum foil. The aluminum foils are referred to as 3003 and some of the foils are made of alloys designated 1150 and 1100 and the steel foil referred to herein is of the same order of thickness as the aluminum foil but perhaps slightly somewhat thicker but it does serve the purpose of the present invention.

In FIG. 4, the can or container A is the same as that described in FIGS. 1, 2 and 3, and is of aluminum, as is also the closure C therefor, and both the inner surfaces of the closure and the container or can respectively are coated with the permeable vinyl lacquer Lz' and L respectively. In this modification of the invention in FIG. 4, instead of utilizing the steel foil F, there is simply used apatch or disc D which, as will be noted, terminates inwardly of the formation of theseam S and no portion of this patch or disc is lactually disposed in the seam.

It will be obvious, therefore, that there are different metals that can be utilized for the body of the can or container and the ends or lid of the container, and the beneficial results mentioned herein be thereby obtained.

The drawings are merely for illustrative purposes and it is to be kept in mind that many different types of metals and alloys are utilizable to carry out the present in- |vention.

In some instances, it may be desirable to use an opening means for the can or container. Such opening means may assume the form as that disclosed in United States Patents Nos. 3,089,609 and 3,089,610, and is to be considered .as part of the invention of this lapplication in combination with the can described herein.

. I claim:

1. An aluminum container for preserving food and beverages, said container having an integral bottom and an aluminum closure double seamed thereon in operative position, a sheet of steel foil secured to the inner surface of said aluminum cover and double seamed therewith; and permeable vinyl lacquer, coating the entire inner exposed surface of said container, the steel foil of the closure 4and extending into said double seam whereby if any metal of the side wall becomes exposed to the contents electrolytic action will take place and said ex-` posed inetal will be coated.

2. An :aluminum container for preserving food and beverages, said container having an inte-gral bottom and an `aluminum closure double seamed thereon in operative position, a disc of steel foil secured to the inner surface of said aluminum cover, the entire peripheral edge of said disc being free of said double seam; and permeable vinyl lacquer, coating the entire inner exposed surface of said container, said closure and disc, and extending into said double seam rwhereby if any metal of the side wall bec-omes exposed to the contents electrolytic action will take place and said exposed metal will be coated.

References Cited by the Examiner UNITED STATES PATENTS 3,120,321 2/1964 McCuskey et al. 220-64 3,130,059 4/1964 Fried et al. 220-64 3,152,717 10/ 1964 Schwaiger 22064 THERON E. CONDON, Primary Examiner. G. T. HALL, Assistant Examiner., 

1. AN ALUMINUM CONTAINER FOR PRESERVING FOOD AND BEVERAGES, SAID CONTAINER HAVING AN INTEGRAL BOTTOM AND AN ALUMINUM CLOSURE DOUBLE SEAMED THEREON IN OPERATIVE POSITION, A SHEET OF STEEL FOIL SECURED TO THE INNER SURFACE OF SAID ALUMINUM COVER AND DOUBLE SEAMED THEREWITH; AND PERMEABLE VINYL LACQUER, COATING THE ENTIRE INNER EXPOSED SURFACE OF SAID CONTAINER, THE STEEL FOIL OF THE CLOSURE AND EXTENDING INTO SAID DOUBLE SEAM WHEREBY IF ANY METAL OF THE SIDE WALL BECOMES EXPOSED TO THE CONTENTS ELECTROLYTIC ACTION WILL TAKE PLACE AND SAID EXPOSED METAL WILL BE COATED. 